UN Secretary-General Ban Ki-moon appealed Friday to governments to step up their response to Europe’s migrant crisis following more drownings at sea and the discovery of migrant bodies in an abandoned truck in Austria.

Ban praised leaders and communities who were taking action to cope with the flow of migrants, but added: “Much more is required.”

“I appeal to all governments involved to provide comprehensive responses, expand safe and legal channels of migration and act with humanity, compassion and in accordance with their international obligations,” he said.

The UN chief said he was “horrified and heartbroken” by the loss of lives in the Mediterranean and the grim discovery of more than 70 bodies crammed inside a truck that was abandoned near the Austrian border with Hungary.

Indications are that many of the victims were Syrian refugees, including children.

Rescuers pulled 76 bodies from the Mediterranean after two boats carrying 500 migrants sank, the latest tragedy in a series at sea.

More than 300,000 people have crossed the Mediterranean so far this year, a large increase from last year, the UN refugee agency said.

“The Mediterranean Sea continues to be a death trap for refugees and migrants,” said Ban in a statement.

The UN chief announced plans to convene a special meeting on September 30, on the sidelines of the UN General Assembly, to discuss global concerns about migration.

“This is a human tragedy that requires a determined collective political response. It is a crisis of solidarity, not a crisis of numbers,” he said.